EP2707223A1

EP2707223A1 - A material for packaging of foodstuff, and a package for foodstuff

Info

Publication number: EP2707223A1
Application number: EP12782683.2A
Authority: EP
Inventors: Leena Kunnas; Kaj Koskinen; Timo Lehmuskallio; Marko Haveri; Markus Saari; Annikki SIRÉN
Original assignee: UPM Kymmene Oy
Current assignee: UPM Specialty Papers Oy
Priority date: 2011-05-11
Filing date: 2012-05-09
Publication date: 2014-03-19
Anticipated expiration: 2032-05-09
Also published as: EP2707223A4; ES2717677T3; FI20115458A7; EP3482930B1; EP2707223B1; FI124104B; ES2867548T3; PL2707223T3; FI20115458A0; WO2012153002A1; FI20115458L; PL3482930T3; EP3482930A1

Abstract

The invention relates to a material (2) for packaging foodstuff, the material comprising paper. Said paper is base paper (4) which has been coated on at least one side with a coating (3) comprising one or more flaky coating pigments and polyvinyl alcohol, wherein the total dry weight of said flaky coating pigment and polyvinyl alcohol comprises 20 to 60 wt% of polyvinyl alcohol, and the total dry weight of said flaky coating pigment and polyvinyl alcohol constitutes at least 70 wt% of said coating (3). Furthermore, the invention relates to a food package (1) comprising said material (2).

Description

A MATERIAL FOR PACKAGING OF FOODSTUFF, AND A PACKAGE FOR FOODSTUFF

Field of the invention

The invention relates to a material for packaging of foodstuff. Further, the invention relates to a package for foodstuff.

Background of the invention

In industry, a large variety of packaging materials are manufactured for packaging foodstuffs. For example, bread is typically packaged in either a package made of a material coated with plastic, a plastic package, or a paper package.

Plastic or a packaging material coated with plastic is normally used when the aim is to keep the foodstuff, such as fresh bread, saleable for several days. A material coated with plastic typically prevents the surface of for example said fresh bread from drying, but at the same time it causes softening of the sur- face of the product.

Paper material, in turn, is typically used when the aim is to keep the surface of the foodstuff, such as fresh bread to be packed, crispy. Thus, said fresh bread typically has to be sold on the packaging day, because otherwise the surface of said bread dries too much and the crust becomes too thick.

Consequently, there is still a need for better packaging materials in the industry. Brief summary of the invention

It is an aim of this invention to present a material which is particularly well suited for the packaging of foodstuffs, such as bread. Further, it is an aim of this invention to present a food package comprising said material. The mate- rial for packaging food, and/or the food package according to the invention can keep, for example, the crust of fresh bread more crispy compared with a plastic package of prior art or a package coated with plastic. Nevertheless, the product packed in the material according to the invention can remain saleable longer than, for example, when a paper bag of prior art is used as the packaging material.

In the solution according to the invention, the material for packaging food comprises

- base paper, and

- a coating on at least one side of the base paper, the coating comprising a flaky coating pigment and polyvinyl alcohol.

To achieve the aim of the invention, the material for packaging foodstuff according to the invention is primarily characterized in what will be presented in the appended claim 1. The food package according to the invention is primarily characterized in what will be presented in the appended claim 15.

In an example, the material according to the invention is intended for the packaging of bakery products, such as hamburgers or pastries. In an advantageous example, the material according to the invention for packaging foodstuffs is intended for the packaging of fresh bread. In a third example, the material for packaging foodstuff according to the invention is intended for the packaging of dry products, such as dried bread and/or crispbread.

The material and the food package according to the invention have several advantages. The material according to the invention can be manufactured in such a way that appropriate water permeability, water vapour permeability as well as air permeability are achieved. This has not been possible with packaging materials of prior art. The material according to the invention for packaging foodstuffs, as well as the food package according to the invention can be manufactured in an environmentally friendly way so that the material and/or food package can be, for example, recycled and/or composted and/or burnt after usage. The product is very suitable for use with foodstuffs, and it may enable the product to be packaged to maintain the desired properties longer, for example the mainte- nance of the crust of fresh bread crispy for a longer time so that the bread is still saleable.

Description of the drawings

In the following, the invention will be described in more detail with reference to the appended drawings, in which:

Fig. 1 shows a material according to an embodiment of the invention for packaging foodstuffs, in a cross-sectional view, and

Fig. 2 shows a food package according to an embodiment.

Detailed description of the invention

In this application, reference will be made to Figs. 1 and 2, in which the following reference numerals are used:

1 food package,

2 material for packaging foodstuffs, packaging material,

3 coating,

4 base paper, and

5 location in the food package where no material 2 has been used. In this application, the term gsm refers to grams per square meter (g/m²).

The term "RH" relates to relative humidity of the air.

The term "flaky coating pigment" refers to coating pigments present in a flaky form. The term "flaky" refers to a structure in which one dimension is substantially smaller than the two other dimensions of the structure. Advantageously, the flaky coating pigment comprises talc, kaolin, and/or mica. According to an advantageous example, the content of kaolin in the flaky coating pigments used in the coating is 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, or 100 wt%, including any ranges and partial ranges. The term "base paper" 4 refers to paper of prior art comprising natural fibres as its main raw material. Further, the base paper may comprise, for example, one or more fillers and/or additives. The base paper is preferably uncoated paper. In an example, the base paper is so-called bag paper, such as so- called machine glazed (MG) paper. One side of MG paper is typically smoother than the other side of the paper.

The term "natural fibre" refers to any plant material that contains cellulose. The natural fibre may be wood-based. The wood may be softwood, such as spruce, pine, silver fir, larch, Douglas fir, or Canadian hemlock; or hardwood, such as birch, aspen, poplar, alder, eucalyptus, or acacia; or a mixture of softwood and hardwood. Other than wood-based raw materials may include agricultural waste, grasses or other plant materials, such as straw, leaves, bark, seeds, legumes, flowers, tops, or fruit, which have been obtained from cotton, corn, wheat, oat, rye, barley, rice, flax, hemp, Manila hemp, sisal hemp, jute, ramee, kenaf hemp, bagasse, bamboo, or reed. Preferably, the natural fibre comprises chemically pulped natural fibre, that is, pulp made in a chemical pulping process. In an advantageous example, the content of chemically pulped natural fibres in all the natural fibres used in the base paper product is thus at least 70 wt%, at least 80 wt% or at least 90 wt%, advantageously at least 95 wt% or 98 wt%. Preferably, all the natural fibres used in the base paper are chemically pulped natural fibres. The diameter of the natural fibres is normally 15 to 25 pm and the length more than 500 μιη, but the present invention is not intended to be limited to these parameters.

The term "PVA" refers to polyvinyl alcohol.

The term "WVTR" refers to water vapour transmission rate, i.e. water vapour barrier at conditions of RH 50%, temperature 23^<C.

The term "KIT" refers to a determining method according to the Tappi standard (Tappi T559 cm02) for paper and paperboard with oil and grease resistance. The term "Cobb" refers to the so-called Cobb value measured according to the standard ISO 535:1991. "Air permeability" is measured according to the standard ISO 5636-5:2003. "Water vapour permeability" is measured according to the standard ISO 2528:1995. The material 2 according to the invention for packaging of foodstuffs comprises base paper 4 coated on one side or both sides. Preferably, the base paper 4 is coated on one side only. The coating 3 comprises flaky coating pigment and polyvinyl alcohol (PVA). In an advantageous example, the grammage of the material 2 according to the invention, comprising base paper 4 and coating 3, is 40 to 80 gsm.

In an example, the flaky coating pigment is substantially dry when it is applied as a coating 3 onto the base paper 4. In another example, the flaky coating pigment is in the form of an aqueous mixture or a so-called slurry when applied as a coating 3 onto the base paper 4.

The properties of a mixture that comprises flaky coating pigment, such as kaolin, and polyvinyl alcohol, can be adjusted, for example by changing the thickness of the coating layer 3 so that the insulating capacity of the coating 3 is typically improved when the thickness of the coating layer 3 is increased.

Furthermore, the properties can be influenced, among other things, by changing the relative contents of the flaky coating pigment and polyvinyl alcohol. When the content of the flaky coating pigment increases in relation to the content of polyvinyl alcohol, the viscosity of the coating typically decreases and its porosity increases.

The relative proportion of one or more flaky coating pigments in the total content of said one or more flaky coating pigments and polyvinyl alcohol is at least 40 wt% (wherein the content of polyvinyl alcohol is not higher than 60 wt% of the total content of said one or more flaky coating pigments and polyvinyl alcohol), more advantageously 45 to 80 wt% (wherein the content of polyvinyl alcohol is 20 to 55 wt%), and even more advantageously 50 to 70 wt% (wherein the content of polyvinyl alcohol is 30 to 50% of the total content of said one or more flaky coating pigments and polyvinyl alcohol).

If the proportion of polyvinyl alcohol to the flaky coating pigment is increased, it may be possible to reduce the total quantity of the coating 3 used. In a cor- responding manner, if the proportion of the flaky coating pigment to polyvinyl alcohol is increased, a thicker coating layer may be needed. The pigment coating can be applied on one side of the base paper, or it can be applied on both sides of the base paper. The pigment coating may comprise a single coating layer, or it may comprise several coating layers, such as two, three or four coating layers. For coating the base paper, it is possible to use solutions of prior art, such as one or more of the following: blade coating, flooded nip application, nozzle application, short dwell time application, rod coating, air brush coating, film transfer coating, curtain coating, or spray coating. In an advantageous example, at least one coating layer is formed by film transfer coating, rod coating, or blade coating. The total (dry) content of the coating of the material according to the invention is preferably 1 to 14 gsm, irrespective of whether the base paper is coated on one side or both sides. In an advantageous example, the content of the coating 3 in the finished material 2 is at least 1 gsm and not more than 7 gsm, more advantageously not more than 6 gsm or 5 gsm. Advantageously, the water vapour transmission rate (WVTR, 23^<0, RH 50%) of the finished mate rial is thus 80 to 400 gsm per day, for example 120 to 280 gsm per day. Advantageously, the grease resistance of the finished material, measured by the Oil Unger (60 s) method, is thus 1.3 to 1.8, for example 1.4 to 1.6. Advantageously, the water resistance of the finished material, measured by the Cobb (1800 s) test, is thus 20 to 45, for example 22 to 30. Advantageously, the KIT value of such material is thus 1 to 2. In an advantageous example, the ratio between the flaky coating pigment and PVA (pigment PVA) is thus between 50:50 and 70:30. The material 2 having one or more of the above-mentioned properties may be suitable for the packaging of, for example, fresh bread.

In an advantageous example, the content of the coating 3 in the material 2 is 6 to 14 gsm, for example 8 to 12 gsm. Advantageously, the water vapour transmission rate (23Ό, RH 50%) of the finished ma terial 2 is thus 2 to 12 gsm per day, for example 3 to 8 gsm per day. Advantageously, the grease resistance of the material 2, measured by the Oil Unger (60 s) method, is thus 0.3 to 1.3, more advantageously 0.3 to 0.7. Advantageously, the water resistance of the material 2, measured by the Cobb (1800 s) test, is thus 17 to 35, for example 18 to 25. In an example, the KIT value is thus 4 to 9, for example 5 to 8. In an advantageous example, the coating pigment to PVA ratio of such a material 2 is formed so that the content of PVA is at least 40 wt% or at least 50 wt%. A material 2 having one or more of the above listed properties may be suitable for the packaging of bakery products, such as, for example, greasy and dry foodstuffs and/or greasy and moist foodstuffs. Such foodstuffs may include, for example, hamburgers or pastries. As the content of the coating 3 increases, the grease resistance of the material 2 is typically improved, which is useful, for example, in the packaging of greasy products.

The pigment coating according to the invention may also comprise other substances than one or more flaky coating pigments and polyvinyl alcohol. In an advantageous example, the total content of the flaky coating pigment and polyvinyl alcohol in the coating 3 (calculated as dry substance) is at least 70 wt% or at least 75 wt%, more advantageously at least 80 wt% or at least 85 wt%, and most advantageously at least 90 wt% or at least 95 wt%. Preferably, the coating 3 consists totally or substantially totally of one or more flaky coating pigments and polyvinyl alcohol. The coating material 2 according to the invention can be used for forming a food package 1. In an advantageous example, the food package 1 is a bag or has a substantially bag-like shape. The food package 1 may or may not also comprise one or more other materials 5 than the material 2 according to the invention, for example as a so-called "window". However, even in such a case, the content of the material 2 according to the invention is at least 50%, more advantageously at least 60% or at least 70%, and most advantageously at least 80% or at least 90% of the surface area of the outer layer of said food package . In an example, the material 2 for packaging foodstuffs is used for packaging fresh bread. In another example, the material 2 for packaging foodstuffs is used for packaging bakery products, such as hamburgers or pastries. In a third example, the material 2 is used for packaging dry products, such as dried bread and/or crispbread. Example

Pilot tests were carried out on three different material samples according to the invention and two materials of prior art. In the first sample according to the invention, "Barrier paper 1 ", the coating content was 4 gsm. In the second sample according to the invention, "Barrier paper 2", the coating content was 3 gsm. In the third sample according to the invention, "Barrier paper 3", the coating content was 2 gsm. The materials of prior art comprised an uncoated bread bag paper and a bread bag paper coated with bioplastic.

Water vapour transmission rate, water permeability and air permeability were measured from all materials. These results can be read in Table 1. Furthermore, fresh bread packed in each material was examined after three days from packaging of said fresh bread.

Table .

As seen in Table 1 , the water vapour transmission rate of the materials 2 according to the invention and the products 1 was clearly different from that of the materials and products of prior art in such a way that the water vapour transmission rate of materials according to the invention was clearly lower than in solutions of prior art. The Cobb value measured for materials according to the invention was similar to or lower than the value for uncoated bread bag paper, and higher than the value for bread bag paper coated with bioplastic. Air permeability was clearly lower for the materials according to the invention than for uncoated bread bag paper, but higher than for bread bag paper coated with bioplastic.

The crusts of fresh loafs of bread packed in materials according to the inven- tion were still suitably thin and simultaneously crispy at the end of the three- day observation period. However, the crust of bread packed in uncoated bread bag paper was too hard and too thick after storage for three days. The crust of bread packed in material coated with bioplastic was moist (that is, the crust was no longer crispy) and thinner than desired after storage for three days.

The invention is not limited solely to the examples presented in Figs. 1 and 2 and the above description, but it may be modified within the scope of the appended claims.

Claims

Claims:

1. Material (2) for packaging foodstuff, the material comprising paper, characterized in that said paper is base paper (4) coated on at least one side with a coating (3), which coating comprises

one or more flaky coating pigments, and

polyvinyl alcohol,

wherein

the total dry weight of said flaky coating pigment and polyvinyl alcohol contains 20 to 60 wt% of polyvinyl alcohol, and

the total dry weight of said flaky coating pigment and polyvinyl alcohol constitutes at least 70 wt% of said coating (3).

2. The material according to claim 1 , characterized in that the water vapour transmission rate of the material (2) at an air humidity of 50% and a temperature of 23^<C is 80 to 400 g per m ² per day.

3. The material according to claim 2, characterized in that the water vapour transmission rate of the material (2) at an air humidity of 50% and a temper- ature of 23^<C is 120 to 280 g per m ² per day.

4. The material according to claim 2 or 3, characterized in that the Cobb water resistance of the material (2) is 20 to 45.

5. The material according to claim 2, 3 or 4, characterized in that the KIT value of the material (2) is 1 to 2.

6. The material according to any of the claims 2 to 5, characterized in that the content of the coating (3), in dry weight, is 1 to 7 g per m².

7. The material according to claim 1 , characterized in that the water vapour transmission rate of the material (2) at an air humidity of 50% and a temperature of 23^<C is 2 to 12 g per m ² per day.

8. The material according to claim 7, characterized in that the water vapour transmission rate of the material (2) at an air humidity of 50% and a temperature of 23 is 3 to 8 g per m ² per day.

9. The material according to claim 7 or 8, characterized in that the Cobb water resistance of the material (2) is 17 to 35.

10. The material according to claim 7, 8 or 9, characterized in that the KIT value of the material (2) is 4 to 9.

1 1 . The material according to any of the claims 7 to 10, characterized in that the content of the coating (3) in the material (2), calculated in dry weight, is 6 to 14 g per m².

12. The material according to any of the preceding claims, characterized in that the total content of said flaky coating pigment and polyvinyl alcohol includes 25 to 55 wt% of polyvinyl alcohol.

13. The material according to any of the preceding claims, characterized in that said flaky coating pigment comprises at least 50 wt% of kaolin.

14. The material according to any of the preceding claims, characterized in that said base paper (4) is so-called machine glazed (MG) paper.

15. Food package comprising paper, characterized in that at least 50% of said food package (1 ) consists of material (2) in which base paper (4) has been coated on at least one side with a coating (3), the coating comprising one or more flaky coating pigments, and

polyvinyl alcohol,

wherein

16. The food package according to claim 15, characterized in that the age is intended for packaging fresh bread or other bakery products.